FX Fraipont (X) Nov 8, 2011:

to offset to juxtapose with something else, as for purposes of comparison: to offset advantages against disadvantages.
http://dictionary.reference.com/browse/offset

Daniel Marquis Nov 8, 2011:

Question to asker Do you know what the amounts 160, 59 and 101 relate to? This would clarify things.

Daniel Marquis Nov 8, 2011:

Yes, but... ...OFFSET AGAINST translates into French as « en déduction de ou porté en déduction de ». So, there is definitely an idea of DEDUCTION.

Tony M Nov 8, 2011:

Question of logic Whatever the sums involved, the logic of deduction or addition remains the same in EN:

You have an initial operating cost

From this, you deduct the saving made by getting rid of rail transport

But then you have to add back on how much it costs to replace it with a conveyor.

Only then do you see if there has been a nett saving or not. It doesn't matter what the actual figures are — the nett saving might be –ve; in fact, from the figures as given, it seriously made me wonder about that? It looks as if the large cost of the conveyor may possibly wipe out the savings made on rail transport; only Asker can presumably clarify that particular point for us.

I believe this is why the EN deliberately uses 'offset', which doesn't necessarily imply specifically add or subtract.